Help diagnose play in chainset/BB

Discuss light weight issues concerning road bikes & parts.
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Posts: 232
Joined: Sun Oct 30, 2011 5:25 pm
Location: London, UK

by iamalex

Any advice gratefully received...

If I hold the end of the cranks arms I can push and pull them and there is sideways movement of around 2mm. The movement is even, I can pull on one arm and the other will move. It is not flex in the arms. The chainset seems to pivot slightly through the BB. It creaks and I can make it creak by doing just this by hand in the workstand.

- Focus Izalco Max Disc - 18 months old
- Chris King PF30 30mm - installed from new. 4 season UK use. maybe 15000km
- Rotor InPower 3D+ 30mm axle - 3.5 years old.

- To properly isolate this creak I went through all the usual suspects cleaning, greasing or replacing for wear; through axles, chainring bolts, chainring/spider interface, saddle rails, saddle clamp mechanism, seat clamp, pedals, pedal threads, rear freehub replaced and other bearings checked, cassette replaced, chain replaced, cleats checked, shoes checked.
- I stripped and cleaned chainset. Pulled and refit BB.
- There is no lateral play through the BB. Preload nut tightened correctly. Overtightening does not solve the problem.
- Bearings run turn smoothly in BB, no grinding.
- If I assemble the chainset arms+axle outside of the bike there doesn’t appear to be any play in the axle/arm interface.
- There is a slight bit of wear to the anodising on the chainset axle but doesn’t look structural. Doesn’t feel worn when running a finger over.

Next steps:
- Measure chainset axle for wear.
- Replace Chris King plastic bearing spindle sleeves - maybe the plastic has worn/ovalised.

Any thing else before going nuclear and replacing the BB and (hopefully not) the power meter?

by Weenie

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Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

It sounds like the spindle sleeves are worn. This could be caused by too little preload set which causes the spindle to rock in the BB.

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Posts: 232
Joined: Sun Oct 30, 2011 5:25 pm
Location: London, UK

by iamalex

I went ahead and ordered the replacement sleeves for now. I’ve been careful with the preload so I’ll be disappointed if that was the root cause. Fingers crossed.

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